Method of preparing thiazoles



No Drawing.

" mercaptothiazole Patented Aug. 11, 1931 STATES i .TTAN TErPEMA' AND roam :B. SEBRELL, or AKRON, onro, assreuons To rnneoonYEAn H PATENT OFFICE;

TIRE & RUBBERVCOMPANY, or AKRON, 01110, a conronnrron or onro METHOiD OF PREPARING THIAZO-LES I i "5" One object of the invention is to provide afsimple' method of preparing thiazoles whereby the time required for the complete reaction of the basic ingredients is reduced to a m nimum.

" Another object of the invention is toprovide a'method of preparing such compounds which results in {high yields of unusually pure duct-o During ecent years mercaptothiazoles and I various derivatives thereof have become high- 1y important asvu'lcanization accelerators in rubber-compounds. One of the most importantmembers of this class is mercaptobenzo- Hofiman in Berichte, 20, page 1788 (1887).

According to the disclosure of this article, the compound is prepared by refluxing carbon bisulfide and ortho aminothiophenol together for areIativeIy long period of time.

This invention consists in the discovery that if carbon bisulfide' is heated in the presence ofrfre'shly'. formed'amino thiophenol, reaction takes place in a comparatively short period of time and a high yield of nearly pure is obtained. Freshly formed amino thiophenol may most conveniently be prepared by intermixing a deriva tive, such as a sodium salt of amino thiophenol and carbon bisulfide, and then subjecting the 403' derivative to the action of a reducing agent,

such as hydrogen sulfide. In this manner, the freshly formed compound is produced in the immediate presence of carbon bisulfide. The material, while freshly formed, is highly reactive and at once combines with the sodium hydroxide with water, the relative Application filed November 26, 1928. Serial No. 322,080.

proportions of the. ingredients being' five grams-of amino thiophenol, two grams of s0 diumv hydroxide, and cc. of water- Carbon dioxide which has been saturated with.

carbon disulfide is then bubbled through the mixture until the solution becomes neutral. The neutralized solution is next heated under a reflux condenser for a period of six hours.

Upon acidification, practically pure mercaptobenzothiazole is precipitated. The yields obtained are almost quantitative. The reaction for the production of the freshly formed amino thiophenol may berepresented as folows: i

Freshly formed Freshly formed amino thiophenol may also be obtained by treating salts, s'uch as the sodium, potassium or ammonium salts ofaimido thiophenol, with such reducing agents as hydrogen sulfide, or'with an acid, suchas hydrochloric or sulphuric acid. The reac- Freshly formed e A 4 v v +HCI V +Naolwia see.- .511. 1

Freshly formed H Theinvention is notlimitedto'the use of alkaline salts of amino thiophenol for the preparation of freshly formed amino thiophenol, but maybe practicedwith various other derivatives of that compound. An ex- V sacellent method consists in treating diortho diamino' diphenyl disulfide with a reducing splitting of the disulfidemolecule andthe production of two molecules of amino thiophenol in freshly formed state, the reaction proceeding as represented by the following equation:

A Freshly formed To manufacture'dior'tho diainino diphenyl disulfide, aniline and sulphurare mixed in; the ratio of 224 grams of aniline and 140 grams of sulphur. Thismixtureiis heated to a temperature of160 to 180 ,C. under a refluxcondenser for a period of eight to fifteen h'oursi The resulting material, consisting of a s yrupyor tarrymass, is "then subjected to steam distillation, in order to, removed any "volatileconstituents The mass is next ex tracted with concentrated acid (preferably.

hydrochloric). The disulfide compound is thus obtained'in the solute as an acid salt having the formula NHzHOI HCLHzN H v I The salt, upon being neutralized with sodium' carbonate, produces diortho diam-ido diphenyl disulfide in comparatively pure form, which upon being treated with a reducing agent as previously described, yieldsactive amino thiophenol. Substantially the same results may be obtained byreducing the disulfide to amino thiophenyl hydrochloride, and then -'neutralizing the latter with sodium carbonate oran equivalent material.

'4 g. In each of the above cases, if the active amino thiophenol is refluxed in the presence of carbon disulfide, reaction takes place within a relativtly short period of time to form mercaptobenzothiazole. This reaction may be repreisented as follows:

5 Freshly formed November, 1928.

actual trial of themethod that the yields are low. According to the method constituting this invention, the time required for the production of mercaptobenzothiazole from the salts of amino thiophenol is reduced to six hours, and the yields obtained are almost quantitative. 1

. Although we have described in detail only the preferred embodiments of the invention,

it will be app n to those skilled-intake ta that it 'is-not so limited,- but -'that various modifications may be made therein without departing fromthespirit of the invention or .frome the scope. of theappended claims.,,

What 'we claim is: I. A method of producing mercaptobenbothiazoles which comprises subjecting an, al-

kali salt of amino thiophenol;simultaneously;

to the action of carbon dioxide and carbon bisulfide.""'

2. A method of preparing thia'zoleswhich comprises treating an alkali mercapt.'ohenzo-;-v

salt of amino thiophenol with carbon; di-

oxide saturated with carbon bisulfide. 3. A method of. producing mercaptoben'zothiazoles which comprises transforming a salt of amino thiophenol into amino thiophenol and immediately subjecting it to the action of carbon b'isulfide while it. is still highly reactive.

3 4. A method or producing mercaptobenzothiazol'e 'wh-ich'comprises treating an alkali salt offamino thiophenol-with anacid to;pro-

duce freshly formed amino thiophenol inthe.

presence of carbon bisulfide-w 5. A method of producing mercaptobenzothiazoles which comprises treating diortho diamino diphenyl disulfide with acid to pro duce freshly formed amino thiophenol inthe presence of carbon bisulfide;

In witness whereof, we have signed our names.

' Signed at Akron, in the and State of Ohio, U. S. A., this 23rd day of i hereunto wJAN TEPPEMA. 1

' Loam-B. sEB ELL,

countyof Summitv 

